In Windows 10 all systems no matter how they were activated (be it via Upgrade from Windows 7/8.1 or by using a bought Retail or an embedded BIOS aka MSDM license) will be converted to a Digital License which is based on the Hard Ware ID (HWID) of the respective machine. This License is stored at MS Servers and will activate this machine every time it's freshly installed. Only hardware changes will cause the License being invalidated. By binding it to a Microsoft Account (MSA) you will be able to transfer it in latter case.

The process only needs to be performed once per machine. In later installs just skip any key prompts (choose 'I have no product key' during setup) and at first online contact the MS Server will regocnize the HWID and grant activation automatically.

NOTE : When a Volume License version is installed from VLSC or MVS Business ISO, the default Retail/OEM key needs to be inserted to regain acticvation.

It's actually quite simple and doesn't mess with any system files and leaked (*errrm stolen) keys.

The ticket creation has been appropriately refined for each MS SKU edition so that the Manual Method below is fully applicable to all of them. The Automated Method has been included as well for an easiest activation and works with all MS SKU editions and was specifically devised for the following ones: